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Tampa Bay Water Changes its Disinfectant Residual

In 2002, Tampa Bay Water will stop using chlorine as its disinfectant residual and will begin using chloramines in its treatment of drinking water. After initial treatment with a primary disinfectant, small amounts of a secondary disinfectant, or disinfectant residual, must be applied and maintained at all times within the distribution system to kill organisms that could make people sick. Tampa Bay Water will use chloramines as its secondary disinfectant and continue to use chlorine as its primary disinfectant.

While Tampa Bay Water already complies with all current water quality regulations, this change is being made in advance of new, stricter health standards expected to be imposed in the future under the national Safe Drinking Water Act. Chloramines were selected as the method of choice because they are the most cost-effective way of maintaining compliance under the new regulations. The use of chloramines is 20 percent less expensive than alternative methods of treatment, and at the same time reduces the formation of suspected cancer-causing compounds. And, by switching to chloramines, a more consistent water quality will be maintained throughout Tampa Bay Water's wholesale system.

The use of chloramines as a secondary disinfectant is not a new process and has been used for decades in many cities and counties across the country. In fact, 20-25 percent of the local governments within the United States currently use chloramines, and the number is expected to grow due to new regulations. Cities like Denver and Minneapolis have been using them since World War II. In Florida, chloramines are used in 30 utilities, including the Miami-Dade area of south Florida. 

The change to chloramines will reduce the level of some regulated disinfection by-products formed when chlorine mixes with trace quantities of naturally occurring organic substances found in water. This is particularly significant because the use of chloramines will reduce the formation of trihalomethanes (THMs) and haloacetic acids (HAAs), two types of by-products suspected to cause cancer with prolonged exposure.

This change will not impact all Tampa Bay area residents in the same way. Any noticeable changes will depend on the type of final disinfectant each member government chooses to use and whether the chosen treatment differs from that member government's existing practices. A final disinfectant is necessary because the residual decreases with time and may disappear completely.The following is a list of anticipated changes:

The City of Tampa already adds chloramines to it water as a final disinfectant, so its customers will not notice a change.
 
Hillsborough County began providing chloraminated water to residents of north Hillsborough County in October 2001 and will continue providing water treated with free chlorine to residents of south-central Hillsborough County for the next few years, so only some of its residents may notice a change.
 
Pinellas County, Pasco County and the City of St. Petersburg will begin treating their water with chloramines, so their residents may notice a change.
 
New Port Richey, along with certain other areas that receive water from isolated sources, won’t receive any chloraminated water from Tampa Bay Water, so those residents will not be affected.

Municipalities that purchase water from Tampa Bay Water’s members (listed above) will be affected accordingly.

Those member governments that do switch to chloramines as a final disinfectant will need to make some equipment changes at their treatment facilities

Residents who will be receiving chloraminated water for the first time may notice a change in taste or odor. Chlorine will become much more difficult to detect. Other temporary impacts may be noticed in isolated areas as the chloraminated water is introduced into the member governments' retail distribution systems. Some customers may notice a temporary variation in water color as well as possible sediment in the water. These temporary impacts to water quality are similar to those experienced when a water main is replaced or routine maintenance is performed on the water distribution system and will cease as the system stabilizes. 

Chloramines, like chlorine, must be removed from water before it is used for two specific purposes. Those purposes include:

  -- Kidney dialysis treatments and
  -- Keeping live fish, such as in an aquarium or pond

Since the process for removing chloramines is different from some of the methods used to remove chlorine, medical facilities and dialysis units, as well as pet shops, seafood merchants, restaurant managers and area attractions featuring marine life will be notified in ample time to prepare for the conversion. (For more detailed information click If You Are On Dialysis or If You Own Fish.)

As this change will affect many people in the Tampa Bay region, some background on Tampa Bay Water and its operations may be helpful.

 

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